“There are a lot of stories about people with imaginary friends but I couldn’t find any about the imaginary friend him or herself,” Colfer says. “I tend to do that in my books, to move the nerd or the bad guy centre stage, so this is the next step: taking the character who would be discarded at some point when his friend finds a real friend and making him the lead character.”

Imaginary Fred will be available on the 29th September, and is published by HarperCollins.